Novel nanoporous membranes of bio-based cellulose acetate, poly(lactic acid) and biodegradable polyurethane in-situ impregnated with catalytic cobalt nanoparticles for the removal of Methylene Blue and Congo Red dyes from wastewater

Abstract

The discharge of contaminants of emerging concern (CECs) into water streams is becoming a major global issue. Herein, novel nanoporous membranes of bio-based cellulose acetate, poly(lactic acid) and biodegradable polyurethane in-situ impregnated with catalytic cobalt nanoparticles were synthesized and tested for the removal of Methylene Blue (MB) and Congo Red (CR) dyes from water. The bio-based polymers supported the formation of a network hydrogen bonding among different functional groups as confirmed using FTIR, which improved the membrane stability. Porogen was used to create nanopores within the film bulk, which were used to impregnate the membranes with cobalt nanoparticles that ensured the adsorption, degradation and removal of the hazardous contaminants from polluted water. Up to almost 60% of each of MB and CR were removed under UV irradiation, while adsorption was well described by the Linear and Langmuir isotherms, respectively. The thermodynamic study showed that the adsorption process is dissociative and, thus, involves photocatalytic dye degradation. Both dyes exhibited the same overall rate of adsorption, but CR showed a faster diffusion rate as predicted by the intra-particle diffusion model. Loading the nanoparticles into a biopolymeric matrix could potentially reduce the risks of their environmental release as free particles in water effluents.